Method of eliminating foam in paper manufacture



Patented May 5, 1931 UNITED STATES PATENT OFFICE HAROLD ROBERT RAFTON, 0F LAWRENCE, MASSACHUSETTS, ASSIGNOR TO RAFFOLD PROCESS CORPORATION, A CORIPORATION OF MASSACHUSETTS METHOD OF ELIMINATING FOAM IN PAPER MANUFACTURE {No Drawing.

This invention relates to and has for its principal object a method for the reduction, elimination, prevention, or alteration of foam in the manufacture of a substantially unsized. carbonate filled paper.

An important object of this invention is the improvement of machine operation particularly as regards the dandy roll.

A further object is the improvement in the quality of the paper produced.

Other objects and advantages of this invention will become apparent during the course of the following description.

In my copending application Serial No. 202,453 of June 29, 1927, I have disclosed a method for the reduction, elimination, prevention, or alteration offoam in some cases where carbonate fillers are used in paper making by the employment of starch or starch and alum.

The present invention relates to a new method applicable under similar conditions, but is confined to the manufacture of unsized carbonate filled papers.

In some cases when carbonate fillers of the character hereinafter referred to are incorporated into a paper'mix of a character suitable for preparing substantially unsized paper, and this mix is run off on a web-forming device, such as the screen of a Fourdrinier machine, a considerable amount of foam is produced during the process and particularly at the wet end of the paper machine. If the mix in this condition is run on to the web-forming device an excessive amount of foam will be present thereon with the result that an inferior grade of paper is produced. Sometimes, even if there is no important amount of foam apparent on the Web as it is being formed on the wire, the stock seems to be of such a nature that foam is formed by the action'o'f the dandy roll as it rides on the web. Moreover, I have found that when running certain unsized stocks containing carbonate fillers, particularly stocks containing old papers, there is a tendency for the dandy roll to fill up which results after a time in its picking up pieces of the paper web with the result that the web is broken and the dandy roll must be flushed out. It will be apparent that Application filed September 5, 1928. Serial No. 304,174.

these disadvantageous features result in inconvenience and substantially reduced economy of the process.

In my copending application Serial No. 304,171, filed Sept. 5, 1928, I have described and claimed a process wherein, according to the preferable procedure, the elimination of foam and dandy trouble experienced in some cases in making substantially unsized paper filled with carbonate filler, is efiected by the use of a small amount of saponified material, as sodium resinate, and acidic material, as alum, added in the beater, followed by the addition of acidic material, as alum, at the wet end of the paper machine, which addition of alum at the wet end of the paper machine acts in restoring the beneficial effect of the reaction of sodium resinate and alum, which effect has been deteriorated, sometimes even to the point of destruction, by the action of the carbonate filler.

I have now discovered that the foam normally present or producible in paper stocks referred to above containing carbonate filler which are used for making substantially unsizedpaper can be substantially reduced in amount if not completely eliminated, or can be altered in character so that the presence of the foam on the web-forming device of the paper machine is not objectionable by adding tothe mix while in the beater or similar machine or to a mixer or similar device where a beater is not employed a suitable agent such as sodium resinate and subsequently treating the mix with a suitable precipitant such as alum at the wet end of the paper machine.

In the preferred practice of my process I, add in the beater to a fibrous mix of any character suitable for use in manufacturing unsized paper and which contains carbonate filler, a small amount of sodium resinate. The amount of sodium resinate added is less than that amount which if precipitated by alum would produce a substantially sized paper. As will be apparent other ingredients such as coloring matter may be added to the mix at this point. The mix is then passed through the usual preliminary steps of the paper process and at or subsequent to the point that the mix is largely diluted prior to its passage on to a web-forming device, alum is added to the mix preferably continuously, preferably in solution. The mix is then passed on to a Web-forming device in the usual manner and I have discovered that the foam which was formerly present in the mix, particularly at the Wet end of the paper machine, is substantially eliminated or so altered that it causes substantially no trouble on the web-forming device. Moreover, by treating the mix in the manner described the tendency of the dandy roll to fill up in a relatively short time and to pick up pieces of the paper web is substantially eliminated.

It is necessary as indicated to add the alum at or subsequent to the point of dilution of the mix, as I have found that if it be added when the mix is in relatively concentrated condition, and particularly when the relatively concentrated mix is subjected to agitation as is normal in stock chests, the foam eliminating effect is very quickly deteriorated even to the point of complete destruction. The foam eliminating effect even when the mix is in the diluted condition is gradually deteriorated, but is substantially unaffected within the time limits that the mix is maintained in the dilute state in the usual papermaking procedure. Moreover, although agitation in the dilute state hastens to a certain extent the deterioration ofthe foam eliminating eflect, the speed of deterioration is not nearly so pronounced as in the concentrated condition, and from a practical standpoint I have found that the agitation to which the diluted mix is subjected prior to delivery onto the web-forming device does not deteriorate the foam eliminating effect to a substantial degree. Thus, it is apparent that the foam eliminating effect is obtained by adding the alum under conditions favoring the minimizing of the time and or intimacy of contact of the alum with the constituents of the paper mix.

Of course the sodium resinate may be added at any point prior to web formation other than in the beater, even after the addition of the alum, but experiments do not indicate that any substantially better foam eliminating effect is obtained thereby, and such addition therefore can be considered the substantial equivalent of adding sodium resinate in the beaten,

The alum solution need not be added directly to the fibrous mix, but can be added to the fresh water or white water, e. g. tray water, with which the mix is diluted. If the alum be added to the tray water, only a brief time interval should elapse before the so treated tray water is used for dilution.

Although substantially more foam is produced in the herein described process up to the point of alum addition at the wet end of the paper machine than in the process referred to in my copending application. Serial No. 304,171, of Sept. 5, 1928, (except possibly in that modification wherein the sodium resinate would be'added at the Wet end of the paper machine after the alum addition), nevertheless the foam is altered in character by the alum before the mix is passed onto the web-forming device, so that what foam is not held back in the rifiiers orv the like is of such nature that it causes substantially no trouble during the formation of the web, and the paper produced by this process is substantially foam free. Moreover, inasmuch as the amount of alum used in the present process is somewhat less than that used in the process set forth in my copending application referred to directly above, the present process therefore results in a more economical operation.

An illustrativefurnish suitable for use in the practice of my process is as follows:

Materials added in beater Pounds Fibrous furnish, e. g. approximately equal parts of sulphite, soda, and old paper stocks 1644 Sodium resinate 6 Carbonate filler, e. g. calcium carbonate'magnesium hydroxide 356 Material added to mid proportionately and continuously on dilution Pounds Alum 45 Another suitable furnish is:

Materials added in beater Pounds Fibrous furnish, e. approximately equalpartsof-sulph1teandsodapulps 164A Sodium resinate. 6 Carbonate filler, e. g. calcium carbonate magnesium hydroxide 356 Material added to m/Zw proportionately and continuously on dilution P ounds Alum 35 In the above formulae, the Weights of sodium resinate and carbonate filler refer to the bone dry basis, the weights of all other ingredients being given on the air dry basis.

As indicated by the foregoing the primary object of my invention is to maintain the effect produced by a precipitant such as alum in a paper mix containing carbonate filler. If alum were added under conditions ordinarily obtaining in paper mixes, it would react chemically with the carbonate filler and thusbe destroyed. However, I am able to obtain the desired effect of this alum in the paper mix by adjusting conditions under which the alum is added so as to substantially prevent it from reacting chemically with the carbonate filler. There is therefore substantially no conversion of the carbonate filler into a neutral compound by reaction with the alum added under these conditions, and the carbonate filler continues to exist in the mix. Whereas I have not limited myself to any "definite amount of carbonate filler nor any definite amount of alum to be added under these conditions, the illustrative furnishes given herein indicate that normally the carbonate filler constitutes a substantial precentage of the total furnish and consequently of the paper roduced, and that it is present in the furnish in an amount greatly in excess of the stoichiometrical equivalent of the alum thus added. Thus it will be noted that even were conditions s'uch that reaction between the alum thus addedand the carbonate filler could take place and go to completion,which is substantially not the case in my invention, the final result would not be a neutralization of the mix but rather a using up of thisalum and the mix would remain on the alkaline side owing to the excess carbonate filler present. It is thus apparent that my process, in which a paper isprod-uoed containing a substantial quantity of carbonate filler, is wholly unrelated to any paper making procedure wherein alum or the like is added to a paper mix for the purpose of substantially neutralizing the same so that the final paper will contain substantially no alkaline constituents.

I have discovered that in place of alum I may use with a measure of success certain acidic materials such as sulphuric acid (H 80 or acid salts such as sodium bisulphate (NaHsOi), or other salts of aluminum. Of the aluminum salts available the chloride or the like, or the double salts which are the true alums, may be used, but because of economy I prefer to use the ordinary sulphate of aluminum, commonly called alum.

In place of sodium resinate I may employ other soaps, for example the oleates, or any other material derived by treatment wit an alkaline substance or the like from material originally of acid characteristics or from material which likewise is of a partly or completely'saponifiable nature, such for example as saponlfied beeswax.-

By the term carbonate filler as employed herein is intended to be included calcium carbonate, of which lime mud from the causticizing process is one form; calcium carbonate magnesium basic carbonate employed in the paper disclosed in my U. S. Patent No. 1,595,416; calcium carbonate magnesium hydroxide disclosed in my U. S. Patent No. 1,415,391; or other substantially water insoluble normal or basic carbonates oi alkaline earth metals, (which expression is herein intended to include magnesium), or.

compounds, or double salts, or physically associated mixtures of these with one or more other acid' soluble materials of a substantiallywater insoluble nature. The term carbonate filler is also intended to include fibrous material and/or other material such as paper coating constituents or the like con- 'taining one or more compounds of the character above referred to, such as old papers or similar papers broke, or the like.

By the term wet end of the paper machine is intended to be included those instrumentalities provided in paper manufacture by which and/or in which a relatively concentrated pa er mix is diluted, and treated, conveyed or ed up to the point of web formation, such as the mixing box, regulating and proportioning devices, rililers, troughs, screen's, machine head boxes, inlets and the like, including also instrumentalities used in the white water cycle. 1

Where I use the term sodium resinate it is to be understood thatI mean it to include any material produced by the action of alkali, generally in aqueous solution, on rosin, or on natural or synthetic resin acid or acids, regardless of the exact composition of the product, or the varying composition which difier-- ent samples may possess.

When I use the word paper herein, I use it in the broad sense to include products of manufacture of all typesand of all weightsv and thicknesses, which contain as an essential constituent a considerable amount of prepared fibre and which are-capable of being produced on a Fourdrinier, cylinder, or other forming, felting, shaping or molding machine.

In the claims, where I'use the expression eliminating foam, I mean to include not only those cases in which the foam is-wholly or almost wholly eliminated, but also those in which the amount of foam formed is reduced, those in which the character of the foam is so changed that it breaks with relative ease, those in which foam is from forming, and also cases in WhlCh two or more of the above possibilities are operative.

WhileI have described in detail the preferred practice of my process it is to be understood that the details'of procedure, the proportions of ingredients, and arrangement of steps may be widely varied without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

revented 1. The method of manufacturing substanterial, said saponified material being added in an amount insuflicient to produce a su\bstantially sized paper, thereafter adding to the resulting mix an acidic material at the wet end of the paper machine, and thereafter making paper therefrom.

3. The method of manufacturing substantially unsized paper filled with carbonate filler comprising mixing with fibrous material carbonate filler and sa-ponified material, said saponified material being added in an amount insufficient to produce a substantially sized paper, thereafter adding to the resulting mix a salt of aluminum at the wet end of the paper machine, and thereafter making paper therefrom.

4. The method of manufacturing substantially unsized paper filled with carbonate filler comprising mixing with fibrous mate rial carbonate filler and saponified material, said saponified material being added in an amount insufficient to produce a substantially sized paper, thereafter adding to the resulting mix alum at the wet end of the paper magh ine, and thereafter making paper thererom.

5. The method of manufacturing substantially unsized paper filled with carbonate filler comprising'mixing with fibrous material carbonate filler and sodium resinate, said sodium resinate being added in an amount insuflicient to produce asubstantially sized paper, thereafter adding to the resulting mix alum at the wet end of the paper machine,

and thereafter making paper therefrom.

6. The method of eliminating foam in the manufacture of substantially unsized paper filled with carbonate filler comprising adding to a heater containing fibrous material earbonate filler and sodium resinate, said sodium resinate being added in an amount insufiicient to produce a substantially sized paper, thereafter adding to the resulting mix alum at the wet end of the paper machine, and thereafter making paper therefrom.

7. The method of eliminating foam in the manufacture of substantially unsized paper filled with carbonate filler comprising mixing with fibrous material carbonate filler comprising alkaline earth metal carbonate, and sodium resinate, said sodium resinate being added in an amount insufiicient to produce a substantially sized paper, thereafter adding to theresulting mix alum at the wet end of the paper machine, and thereafter making paper therefrom.

8. The method of eliminating foam in the manufacture of substantially unsized paper filled with carbonate filler comprising mixing with fibrous material carbonate filler comprising calcium carbonate, and sodium resinate in an amount insutficient to produce a substantially sized paper, thereafter adding to the resulting mix alum at the wet end of the paper machine, and thereafter making paper therefrom.

9. The method of eliminating foam in the manufacture of substantially unsized paper filled with carbonate filler comprising mixing with fibrous material carbonate .filler comprising calcium carbonate and magnesium compound, and sodium resinate in an amount insufficient to produce a substantially sized paper, thereafter adding to the resulting mix alum at the wet endof the paper machine, and thereafter making paper therefrom.

10. The method of eliminating foam in the manufacture of substantially unsized paper filled with carbonate filler comprising mixing with fibrous material carbonate filler comprising calcium carbonate magnesium hydroxide, and sodium resinate in an amount insufficient to produce a substantially sized paper, thereafter adding to the resulting mix alum at the wet end of the paper machine, and thereafter making paper therefrom.

11. In a method of the character described, the step of adding to a paper mix containing fibrous material, carbonate filler, and an amount of saponified. material insufficient to produce a substantially sized paper, a precipitant at the wet end of the paper machine..

12. In a method of the character described, the step of adding to a paper mix containing fibrous material, carbonate filler, and an amount of sodium resinate insufficient to produce a substantially sized paper, alum at the wet end of the paper machine.

13. The method of eliminating foam in the manufacture of substantially unsized paper filled with carbonate filler comprising mixing with fibrous material, at least a portion of which' is old paper stock, and carbonate filler, which otherwise would cause trouble with the dandy roll in paper manufacture, saponified materialin an amount insuificient to produce a substantially sized paper, and a precipitant at the wet end of the paper machine.

14. The method of eliminating foam in the manufacture of substantially unsized paper filled with carbonate filler comprising mixing with fibrous material, at least a portion of which is old paper stock, and carbonate filler, which otherwise would. cause trouble with the dandy roll in paper manufacture, sodium resinate in an amount insufiicient to produce a substantially sized paper, and alum at the wet end of the paper machine.

In testimony whereof I affix my signature.

HAROLD ROBERT RAFTON. 

